Regulating system



Aug. 21, 192s. 1,681,519

J. R. CRAIGHEAD REGULATING` SYSTEM Filed Aug. 2, 1926 PL2. l. F'Lg.

Inventor: James RCraLghead,

D 9 @M T/yf l-ILs Attorrweg.

Patented Aug. `21, 1928A,

UNITED STATES Lesina PATENT OFFICE- JAMES R. CRAIG-HEAD, OFSCHENECTA'DY, NEW YORK, ASSIGNOR `T0 GENERAL ELEC- TR'IO COMPANY, 'ACORPORATION OF NEW YORK.

REGULATING SYSTEM.

Application mea august 2,'1926. serial Nn. 126,382.

My inventionl relates to regulating systems and more particularly tovoltage regulating.

other branch being a comparatively small` load whose effect on theregulation of the transformer is small. It is evident that if both loadsare connected in multiple to the transformer secondary, changes in theheavy load,

as for instance, elevator motors will causechanges in the voltageapplied to the small load comprising translating devices which, forinstance, may be incandescent lamps. Since incandescent lamps aresensitive to voltage variations, objectionable'lamp flicker will occur.'lhe foregoing illustration of elevator motors and incandescent lamps isparalleled in potential transformer practice by a heavy load consistingof a synchronism indicator and a light load comprising translatingdevices such as a voltmeter and wattmeter. 1n either case, it is equallydesirable that the regulation of the transformer shall not cause thevoltage on the load of constant-voltage char-l acteristics to vary.

An obj ect of my invention is to prevent objectionable variations in thevoltage impressed on load circuits which require substantially constantvoltage when said load circuits are energized in parallel from the sametransformer with load circuits having electrical characteristics whichcause variations in the ratio of voltage transformation and phase angleof said transformer.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

In the drawing, Fig. 1 is a diagrammatic illustration of an embodimentof my invention, particularly adapted for metering applications; Fig. 2is amodication thereof adapted for general applications; and Fig. 3

is a furthermodification of the arrangement shown in Fig. 2.

Referring to Fig. l of the drawing, 1 indicates the conductors of analternating current supply circuit. A. potential transformer 2 having aprimary winding 3 and a secondary winding 4 is connected to be energizedfrom the supply circuit. A light load device, such as a voltmeter 5, anda comparatively heavy load device, such as a 'synchronism indicator 6,are connected in parallel across the secondary winding 4 of the maintransformer. An auX- iliary transformer 7 having a primary winding 8 anda secondary winding 9 is connected to be responsive to the'voltage ofthe supply circuit 1. The voltmeter 5 is provided with a main actuatingwinding 10 and an'aux'- iliary actuating windingl 11. The main actuatingWinding 10 is connected to be responsive to the voltage across thesecondary winding 4' of the main transformer. The secondary winding 9 ofthe auxiliary transformer is lconnected to the secondary winding 4 ofthemain transformer and through the auxiliary winding 11 ofthe voltmeter tothe other side of the secondary of the main transformer.

The secondary windings 4 and 9 are connected and arranged so that whenthe secondary winding of the main transformer develops the same voltage,with due regard to the ratio of turns, as is supplied to the primarywinding, the resultant voltage of windings 4 and 9 ,will be zero. lVhen,due to the effectof the heavy load 6, the secondary winding 4 of themain transformer develops less voltage, with due regard to the ratio ofturns, tha-n is supplied to the primary winding 3, the difference ofvoltage is applied to the auxiliary coil 11 in such a manner that thetotal effect of the two coils inthe voltmeter will give practically aconstant reading in spite of changes in the heavy load on the maintransi former. The electromotive force produced in the winding 11 isequal to the difference between the supply circuit voltage and the loadcircuit voltage when the supply circuit voltage is divided by thetransformer turn ratio.

Referring to Fig. 2, a somewhat similar ar;

rangement is shown, but in this case the difference of the voltagegenerated by the main transformer 2 and the auxiliary transformer 7 isapplied through a second auxiliary transformer 12, having a primarywinding 13 and a secondary Winding 14. A load circuit 15 of constantvoltage characteristics, shown diagrammatically as incandescent lamps,is connected in'parallelacross the secondary ofthel vload circuit'15. Inthis case the difference in voltage generated by transformers 2 and 7 isapplied to the primary winding 13 of transformer 12 which furnishes avoltage through its secondary winding 14 in seriesY with the voltage ofthe main transformer 2 to maintain a substantially constant voltageacross the incandescent lamp circuit with changes of loady f on themotor circuit.

In' F ig. 3, the main transformer 2 is shown connected in the samemanner as in Fig. 2, but the auxiliary transforming means comprises atransformer 17 having a three-legged core 18., A primary winding 19 ispositioned on one leg a secondary Winding 20 is positioned on anotherleg, and a tertiary winding 21, usually arranged with the same number ofturns as the secondary winding 20, is positioned on the middle leg. Theprimary winding 19 is connected to be energized from the supplycircuit 1. The secondary winding 20 is connected in parallel withthesecondary winding 4 of the main transformer, and the tertiary winding21 is connected in series with the load circuit 15. A variable loadcircuit, shown as a motor load 16, is connected in parallel with theload circuit 15 across the secondary of the main transformer 2.`

The operation of the arrangement shown in Fig. 3 is as follows: If it beassumed that the motor load 16 represents an elevator. motor load orsimilar motor load, starting and acceleration of the motor will requireheavy fluctuating currents which would ordinarily cause poor regulationon the main transformer with consequent variations in voltage impressedacross thelamp circuit. The secondary windings 4 and 2O of thetransformers 2 and 17 respectively are so positioned and arranged thatfor light load conditions, the two secondary windings develop voltageswhich are equal and inopposition. When, due to the-effect of the motorload,-thye secondary winding 4 of the main transformer develops lessvoltage, with due regard to the ratio of turns, than is supplied to itsprimary winding, the auxiliary transformer receives diiferentvvoltageson its primary and secondary windings. If these voltages were equal, theflux developed in the core l18 would pass only through the primarywinding 19 and the secondary winding 20 and I no voltage would begenerated in the tertiary winding. However, since these two voltages areunequal, the flux developed on the primary side of the core 18 will begreater than that developed on the secondary side. and the vunits thanthe main transformer.

dierence in ux will pass through the tertiary coil 21 and generate avoltage proportional to the difference of voltage between the primarywinding 19 and the secondary winding 20. This voltage is introduced inseries with the load circuit 15 and will maintain a substantiallyconstant voltage across the lamp circuit with variations in voltageacross the secondary of the main transformer. It will be apparent,however, that the tertiary winding 21 may be arranged to excite anauxiliary coil in an instrument, similarly to the arrangement shown inFig. 1, instead of introducing a corrective voltage in series with theload of constant voltage characteristics. Whether an auxiliary coil inan instrument is energized by a corrective voltage and a main coil isenerized by the voltage from the main trans- 'ormer, or the resultantvoltage applied directly to translating devices such as instruments orlamps is obtained by introducing a corrective voltagein series with thevoltage from-the main transformer, there is in each case a compositeenergization or effect.

The auxiliary transformers as shown in each of the lfigures may be verymuch smaller It is also to be noted that, since the whole scheme ofcorrection is based Aon the difference between the primary and secondaryvoltages of the main transformer, with due regard to the ratio of turns,the correction will obviously apply to phase angle between primary andsecondary voltage as well as to. ratio. This feature is important forall applications in metering.

While I have shown and described several embodiments of my invention, itwill be obvious tothose skilled in the art that changes andmodifications may be made without dcparting from my invention,-and I,therefore, aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. In combination, an alternating current supply circuit, a transformerconnected to said supply circuit, a load circuit comprising a pluralityof branch circuits connected in parallel to be energized from saidtrans- A former, and means for introducing into one of said branchcircuits an electromotive force proportional to the difference betweenthe supply circuit voltage, divided bythe transformer turn ratio, andthe load circuit voltg2. In combination, .an alternating current supplycircuit, a main transformer connected to said supply circuit, a loadcircuit comprising a plurality of branch circuits connected v Ibranchcircuits', and an auxiliary transformer for interconnecting said supplycircuit and said winding for applying to said winding a voltagedependent upon the difference between the voltage applied to saidauxiliary transformer and the voltage of said load circuit.

3. AIn combination, an alternating current supply circult, a maintransformer connected to said supply circuit, a pluralit .of load cirentupon the difference between the voltage of the secondarl winding of saidauxiliary transformer an load circuits, and means for combining theJenergization vfrom said winding and the voltage of said one of saidload circuitsto pro# duce the effect of a voltage in another of saidload circuits which is substantially unaffected bythe variations inratio of voltage transformation and phase angle of said main transformerupon changes of load in said first-mentioned load circuit.

4. In combination, an alternating current supply circuit, a maintransformer connected to said supply circuit, a plurality of load cir-`cuits arranged to be energized in parallel from said transformer, andmeans for introducing a- 'voltage in series with one of said circuitscomprising a winding connected to be energized in accordance-withchanges in the ratio of transformation of said main transformer due tochanges in load in the other load circuit.

5. In combination, an alternating current supply circuit, a maintransformer connected to said supply circuit, a plurality of loadcircuits connected to be energized in parallel from said maintransformer, an auxiliary transformer having a primary winding connectedto said supply circuit and a secondary I. winding connected to thesecondary winding 0f said main transformer, and a third windingassociated'with the windings of said -auxiliary transformer forsupplying' a corrective voltage to one of said load circuits 1naccordance with the variations in the ratio of voltage transformation ofsaid main transformer from its theoretical value. v

6. In combination, an alternating current supply circuit, a maintransformer connected to said supply circuit, a load circuit of constantvoltage characteristics, and a load circuit of variable currentcharacteristics connected to be energized in parallel from said maintransformer, an auxiliary transformer having a primary winding connectedto said supply circuit and a secondary winding con- Y nected to thesecondarv winding of said main transformer, and a tlird windingassociated with the windings of said auxiliary trans former formaintaining a voltage in said first mentioned circuit substantiallyunaffected by the voltage ,of one of said4 '-7. In combination, analternating currentv supply circuit, a main transformer connected tosaid supply circuit, a circuit from which a load requiring asubstantially constant voltage is energized, a circuit from which a loadrequiring comparatively larger and variable amounts of/power isenergized, said load circuits being arranged to be connected in parallelwith said main transformer, and an auxiliary transformer comprising aprimary winding connected to said supply circuit, a secondary windingconnected to be responsive to the secondary voltage of said maintransformer, and a tertiary winding connected and arranged forintroducing a voltage in `series relation with said first mentionedcircuit in accordance with the variations in the ratio of voltagetransformation of said main transformer from a predetermined value.

8. In combination, an alternating current supply circuit, a maintransformer connected a load requiring a substantially constant voltageis energized, a circuit from which a load requiring varying amounts 0fpower is energized, said load circuits being arranged to be energized inparallel from said main transformer, an auxiliary transformer connectedto said supply circuit and arranged for generating a secondary voltageequal to the open circuit secondary voltage of said main transformer,and a winding in circuit with said first mentioned load ,circuitconnected to be responsive to the difference in voltage between thesecondary windings of said main and auxiliary transformers.

9. In combination an alternating current supply circuit, a maintransformer' connected to said supply circuit, a circuit from whichtranslating devices are energized, a circuit fromwlich a load requiringvarying amounts of power is energized, said circuits being connected tobe energized in parallel from said main transformer, an auxiliarytransformer having a core comprising three winding legs, a primarywinding on one of said legsconnectcd to said supply circuit, a secondarywinding on another of said legs connected to the secondary winding ofsaid main transformer, and means comprisingn a tertiary winding on theremaining leg arranged to producea corrective voltage for supplying inconjunction with said age is energized, a circuit from which a loadrequiring varying amounts of power is enersaidoutside legs connected tothe secondary gized, said load circuits being arranged to be Winding ofsaid main transformer, and a 10 energized in parallel from said maintranstertiary Winding on said intermediate leg for former, an auxiliarytransformer having a supplying a correctivevoltage to said first core'comprising two outside legs and an-inmentioned circuit.

termediate leg, a primary Winding on one of In Witness whereof, I'havehereunto set my said outside legs connected t0 said supply hand this30th day of Julyf1926.

circuit, a secondary winding on the other of A JAMES R. CRAIGHEAD.

